Heat dissipation plate

ABSTRACT

A heat dissipation plate including a heat-conductive material layer, a first metal layer, a metal substrate, and a metal ring frame is provided. The heat-conductive material layer has an upper surface and a lower surface opposite to each other. A material of the heat-conductive material layer includes ceramic or silicon germanium. The first metal layer is disposed on the lower surface of the heat-conductive material layer and has a first rough surface structure. The metal substrate is disposed below the first metal layer and has a second rough surface structure. The metal ring frame is disposed between the first metal layer and the metal substrate. The first rough surface structure, the metal ring frame, and the second rough surface structure define a fluid chamber, and a working fluid flows in the fluid chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 102117918, filed on May 21, 2013. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a heat dissipation plate, and more particularlyto a heat dissipation plate that is suitable for carrying at least oneheat generating element.

2. Description of Related Art

According to a commonly used existing light emitting diode (LED) packagestructure, a LED chip needs to be packaged before use, and a largeamount of heat will be generated while the LED chip emits light. If theheat generated by the LED chip cannot be dissipated and keepsaccumulating within the LED package structure, the temperature of theLED package structure will continuously increase. Thus, due to theexcessive heat, the LED chip may encounter an issue of luminance decay,and the service life of the LED chip may be shortened; what is more,permanent damages to the LED chip may be caused in some cases.

The conventional LED chips are mostly disposed on the heat dissipationplate which uses a metallic circuit to dissipate heat. However, thethermal expansion coefficient of the metallic circuit is much greaterthan the thermal expansion coefficient of the LED chips, i.e., these twothermal expansion coefficients are mismatched. In addition, theincreasing thermal stress and warpage generated by the LED chips maylead to a reliability decrease in the LED chips and the heat dissipationplate. Therefore, how to increase the heat dissipation effect of the LEDchips and improve the reliability of the LED chips and the heatdissipation plate now has become an important issue.

SUMMARY OF THE INVENTION

The invention provides a heat dissipation plate which achieves afavorable heat dissipation effect.

The heat dissipation plate of the invention includes a heat-conductivematerial layer, a first metal layer, a metal substrate, and a metal ringframe. The heat-conductive material layer has an upper surface and alower surface opposite to each other, and a material of theheat-conductive material layer includes ceramic or silicon germanium.The first metal layer is disposed on the lower surface of theheat-conductive material layer and has a first rough surface structure.The metal substrate is disposed below the first metal layer and has asecond rough surface structure. The metal ring frame is disposed betweenthe first metal layer and the metal substrate. The first rough surfacestructure, the metal ring frame, and the second rough surface structuredefine a fluid chamber, and a working fluid flows in the fluid chamber.

In an embodiment of the invention, the heat-conductive material layerfurther includes at least one conductive through hole structure. Theconductive through hole structure exposes a portion of the first metallayer and is electrically connected to the first metal layer.

In an embodiment of the invention, the heat dissipation plate furtherincludes a second metal layer. The second metal layer is disposed on theupper surface of the heat-conductive material layer, and the secondmetal layer entirely covers or exposes a portion of the heat-conductivematerial layer.

In an embodiment of the invention, the heat dissipation plate furtherincludes at least one opening. The opening penetrates through theheat-conductive material layer and the first metal layer andcommunicates with the fluid chamber. A thin metal pipe may be insertedinto the opening for gas suction or fluid injection, such that the fluidchamber is in a low vacuum state; after that, the inserted thin metalpipe is closed.

In an embodiment of the invention, the heat dissipation plate furtherincludes at least one opening. The opening penetrates through the metalring frame and communicates with the fluid chamber.

In an embodiment of the invention, the heat dissipation plate furtherincludes at least one opening. The opening penetrates through the metalsubstrate and communicates with the fluid chamber.

In an embodiment of the invention, a material of the first metal layer,a material of the metal substrate, and a material of the metal ringframe include copper, aluminum, or an alloy thereof.

In an embodiment of the invention, the first rough surface structure isa concave-convex surface structure, and a Rymax of the first roughsurface structure ranges from several micrometers to severalcentimeters.

In an embodiment of the invention, the second rough surface structure isa concave-convex surface structure, and a Rymax of the second roughsurface structure ranges from several micrometers to severalcentimeters.

In an embodiment of the invention, the working fluid includes air orliquid.

Based on the above, the material of the heat-conductive material layerof the heat dissipation plate of the invention is ceramic or silicongermanium having high thermal conductivity. The first rough surfacestructure of the first metal layer, the metal ring frame, and the secondrough surface structure of the metal substrate define a low-vacuum-levelfluid chamber. Accordingly, the heat dissipation plate of the inventioncan be considered as a vapor chamber, and when a heat generating element(such as a LED chip) is disposed on the heat dissipation plate, the heatgenerated by the heat generating element can be dissipated due to thetwo-phase flow characteristics of the vapor chamber. Thereby, the heatgenerated by the heat generating element can be removed effectively, andthe efficiency and the lifetime of the heat generating element may beincreased.

In order to make the aforementioned and other features and advantages ofthe invention more comprehensible, several embodiments accompanied withfigures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic cross-sectional view illustrating a heatdissipation plate according to an embodiment of the invention.

FIG. 2 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention.

FIG. 3 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention.

FIG. 4 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention.

FIG. 5 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention.

FIG. 6 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according to anembodiment of the invention.

FIG. 7 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according toanother embodiment of the invention.

FIG. 8 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according toanother embodiment of the invention.

FIG. 9 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according toanother embodiment of the invention.

FIG. 10 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according toanother embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic cross-sectional view illustrating a heatdissipation plate according to an embodiment of the invention. In FIG.1, a heat dissipation plate 100 a in the present embodiment includes aheat-conductive material layer 110 a, a first metal layer 120, a metalsubstrate 130, and a metal ring frame 140. In detail, theheat-conductive material layer 110 a has an upper surface 112 a and alower surface 114 a opposite to each other; in particular, a material ofthe heat-conductive material layer 110 a includes ceramic or silicongermanium. The first metal layer 120 is disposed on the lower surface114 a of the heat-conductive material layer 110 a and has a first roughsurface structure 122. The metal substrate 130 is disposed below thefirst metal layer 120 and has a second rough surface structure 132. Themetal ring frame 140 is disposed between the first metal layer 120 andthe metal substrate 130. The first rough surface structure 122, themetal ring frame 140, and the second rough surface structure 132 definea fluid chamber C, and a working fluid F flows in the fluid chamber C.

More specifically, the first metal layer 120 described in the presentembodiment is in direct contact with the lower surface 114 a of theheat-conductive material layer 110 a. In the present embodiment, amaterial of the first metal layer 120, a material of the metal substrate130, and a material of the metal ring frame 140 include copper,aluminum, or an alloy thereof, wherein the materials of the first metallayer 120, the metal substrate 130, and the metal ring frame 140 can bethe same or different, and the invention does not pose any limitationthereto. In addition, the fluid chamber C, for example, is alow-vacuum-level chamber, and the working fluid F, for example, is airor liquid.

In particular, the first rough surface structure 122 of the first metallayer 120 described in the present embodiment, for example, is acontinuous concave-convex surface structure or a non-continuousconcave-convex surface structure, and the Rymax of the first roughsurface structure 122 ranges from several micrometers to severalcentimeters. The first rough surface structure 122 may be considered asa capillary structure. On the other hand, the second rough surfacestructure 132 of the metal substrate 130 described in the presentembodiment, for example, is a continuous concave-convex surfacestructure or a non-continuous concave-convex surface structure, and theRymax of the second rough surface structure 132 ranges from severalmicrometers to several centimeters. The second rough surface structure132 may also be considered as a capillary structure. Here, the firstrough surface structure 122 and the second rough surface structure 132,for example, are formed by mechanical processing (e.g., computernumerical control (CNC) milling, stamping, or sandblasting), chemicalprocessing (e.g., electrochemical plating or etching), or physicalgrinding, which should not be construed as limitations to the invention.

The material of the heat-conductive material layer 110 a of the heatdissipation plate 100 a described in the present embodiment is ceramicor silicon germanium having high thermal conductivity, and the firstrough surface structure 122 of the first metal layer 120, the metal ringframe 140, and the second rough surface structure 132 of the metalsubstrate 130 define a low-vacuum-level fluid chamber C. Accordingly, asa heat generating element (not shown) is disposed on the heat-conductivematerial layer 110 a, the working fluid F inside the fluid chamber Cabsorbs heat E generated by the heat generating element and vaporizes ona low vacuum condition. At this time, the working fluid F absorbs theheat E and rapidly expands its volume, and the gas-phase working fluid Fsoon fills the whole fluid chamber C. When the gas-phase working fluid Fis in contact with areas with low temperature, the gas-phase workingfluid F is condensed, so as to allow the heat absorbed duringvaporization to be released. After condensation, the liquid-phaseworking fluid F returns to the evaporating region (i.e., below the heatgenerating element) via a capillary action of the first rough surfacestructure 122 and the second rough surface structure 132. Therefore, viathe repeated cycles of conduction, evaporation, convection, andcondensation, the heat E generated by the heat generating element can berapidly transferred to each portion of the heat dissipation plate 100 a.In short, the heat dissipation plate 100 a described in the presentembodiment can be considered a vapor chamber having a flat structure andthe satisfactory two-phase flow characteristics. Thereby, an excellenttwo-dimensional lateral thermal conduction effect may be provided, theheat generated by the heat generating element may be rapidly diffused toavoid a formation of hot spots in local regions, and the lifetime of theheat generating element may be extended.

On the other hand, the heat-conducting material layer 110 a achievesthermal conduction effects, and the thermal expansion coefficient of theheat-conducting material layer 110 a is relatively close to the thermalexpansion coefficient of the heat generating element (not shown).Therefore, as the heat generating element is disposed on theheat-conductive material layer 110 a, the difference of thermalexpansion coefficients between the heat dissipation plate 100 a and theheat generating element held by the heat dissipation plate 100 a may bereduced, the corresponding stress increase between the heat generatingelement and the heat-conductive material layer 110 a due to thesignificant difference between the two thermal expansion coefficientscan be avoided, the heat generating element may be prevented fromfalling off or being damaged, and the reliability of the heatdissipation plate 100 a may be enhanced.

Several embodiments are provided hereinafter to illustrate thestructural designs of the heat dissipation plates 100 b, 100 c, 100 d,and 100 e. It should be mentioned that the reference numerals and someof the contents in the previous embodiment are used in the followingembodiments, in which identical reference numerals indicate identical orsimilar components, and repeated description of the same technicalcontents is omitted. For a detailed description of the omitted parts,reference can be found in the previous embodiment, and no repeateddescription is contained in the following embodiments.

FIG. 2 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention. InFIG. 2, the heat dissipation plate 100 b in the present embodiment issimilar to the heat dissipation plate 100 a in FIG. 1, and one of maindifferences is that the heat-conductive material layer 110 b in thepresent embodiment has at least one conductive through hole structure116 b (FIG. 2 schematically illustrates three hole structures), and theconductive through hole structure 116 b is connected to the uppersurface 112 b and the lower surface 114 b and exposes a portion of thefirst metal layer 120. The conductive through hole structure 116 b iselectrically connected to the exposed portion of the first metal layer120. In addition, the heat dissipation plate 100 b further includes atleast one opening H1, wherein the opening H1 penetrates through themetal substrate 130 and communicates with the fluid chamber C to improvethe overall heat dissipation efficiency of the heat dissipation plate100 b by sucking gas from or injecting fluid into the fluid chamber Cthrough the opening H1. A thin metal pipe (not shown) may be insertedinto the opening H1 for gas suction or fluid injection, such that thefluid chamber C is in a low vacuum state; after that, the inserted thinmetal pipe is closed.

FIG. 3 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention. InFIG. 3, the heat dissipation plate 100 c in the present embodiment issimilar to the heat dissipation plate 100 a in FIG. 1, and one of maindifferences is that the heat dissipation plate 100 c in the presentembodiment further includes a second metal layer 160 a. The second metallayer 160 a is disposed on the upper surface 112 a of theheat-conductive material layer 110 a, and the second metal layer 160 aentirely covers the heat-conductive material layer 110 a.

In addition, the heat dissipation plate 100 c further includes at leastone opening H2. The opening H2 sequentially penetrates through thesecond metal layer 160 a, the heat-conductive material 110 a, and thefirst metal layer 120 and communicates with the fluid chamber C toimprove the overall heat dissipation efficiency of the heat dissipationplate 100 c by sucking gas from or injecting fluid into the fluidchamber C through the opening H2.

FIG. 4 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention. InFIG. 4, the heat dissipation plate 100 d in the present embodiment issimilar to the heat dissipation plate 100 a in FIG. 1, and one of maindifferences is that the heat dissipation plate 100 d in the presentembodiment further includes a second metal layer 160 b. The second metallayer 160 b is disposed on the upper surface 112 a of theheat-conductive material layer 110 a, and the second metal layer 160 bcovers the heat-conductive material layer 110 a and exposes a portion ofthe upper surface 112 a of the heat-conductive material layer 110 a. Inaddition, the heat dissipation plate 100 d further includes at least oneopening H3, and the opening H3 penetrates through the metal ring frame140 and communicates with the fluid chamber C to improve the overallheat dissipation efficiency of the heat dissipation plate 100 d bysucking gas from or injecting fluid into the fluid chamber C through theopening H3.

FIG. 5 is a schematic cross-sectional view illustrating a heatdissipation plate according to another embodiment of the invention. InFIG. 5, the heat dissipation plate 100 e in the present embodiment issimilar to the heat dissipation plate 100 b in FIG. 2, and one of maindifferences is that the heat dissipation plate 100 e in the presentembodiment further includes a second metal layer 160 b. The second metallayer 160 b is disposed on the upper surface 112 b of theheat-conductive material layer 110 b, and the second metal layer 160 bcovers the heat-conductive material layer 110 b and exposes a portion ofthe upper surface 112 b of the heat-conductive material layer 110 b.

Furthermore, the conductive through hole structure 116 b, the secondmetal layers 160 a and 160 b, and the openings H1, H2, and H3 are alsoapplicable in other embodiments not shown herein. According to the abovedescriptions in the previous embodiments, people having the ordinaryskill in the art can use the aforementioned components to achieve thedesired technical effects based on the actual requirements.

FIG. 6 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according to anembodiment of the invention. In FIG. 6, the heat dissipation plate 100 ais suitable for carrying a LED chip 200 a (i.e., the heat generatingelement), and the LED chip 200 a is embedded in a dielectric layer 210and electrically connected to circuits 230 on the dielectric layer 210through a plurality of bonding wires 220. Moreover, the LED chip 200 aand the dielectric layer 210 are fixed onto the upper surface 112 a ofthe heat-conductive material layer 110 a by an adhesive layer 240. Here,the adhesive layer 240, for example, can be a conductive adhesive layeror a non-conductive adhesive layer, and the invention does not pose anylimitation thereto.

The heat-conductive material layer 110 a in present embodiment achievesthe heat dissipation effects, and the thermal expansion coefficient ofthe heat-conductive material layer 110 a is close to the thermalexpansion coefficient of the LED chip 200 a (not shown). Therefore, asthe LED chip 200 a is disposed on the heat-conductive material layer 110a by the adhesive layer 240, the difference of thermal expansioncoefficients between the heat dissipation plate 100 a and the LED chip200 a held by the heat dissipation plate 100 a may be effectivelyreduced, the corresponding stress increase between the heat generatingelement and the heat-conductive material layer 110 a due to thesignificant difference between the two thermal expansion coefficientscan be avoided, the LED chip 200 a may be prevented from falling off orbeing damaged, and the reliability of the heat dissipation plate 100 amay be enhanced. Furthermore, if the heat dissipation plate 100 a onlyhas the function of heat dissipation, the heat generated by the LED chip200 a may be rapidly transmitted to the external surroundings throughthe cycles of conduction, evaporation, convection, and condensation.

It is worth to mention that the invention does not limit the number ofthe LED chips 200 a, although only one LED chip 200 a is exemplifiedherein. However, with reference to FIG. 7, in another embodiment, theheat generating element can also be composed of a plurality of LED chips200 b connected in series or in parallel. This still belongs to atechnical means adoptable in the invention and falls within theprotection scope of the invention.

FIG. 8 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according toanother embodiment of the invention. In FIG. 8, the heat dissipationplate 100 d is suitable for carrying a LED chip 200 d (i.e., the heatgenerating element), wherein the LED chip 200 d is disposed on thesecond metal layer 160 b, and the LED chip 200 d is structurally andelectrically connected to the second metal layer 160 b through aplurality of bonding wires 220. Here, the heat dissipation plate 100 dnot only has the function of heat dissipation but also has the functionof electrical conduction.

FIG. 9 is a schematic cross-sectional view illustrating a heatdissipation plate which holds a heat generating element according toanother embodiment of the invention. In FIG. 9, the heat dissipationplate 100 d is suitable for carrying a LED chip 200 e (i.e., the heatgenerating element), wherein the LED chip 200 e is disposed on thesecond metal layer 160 b through the silver paste 250; that is, the LEDchip 200 e is electrically connected to the second metal layer 160 b ofthe heat dissipation plate 100 d by flip chip bonding. Here, the heatdissipation plate 100 d not only has the function of heat dissipationbut also has the function of electrical conduction.

It is worth to mention that the invention does not limit the number ofthe LED chips 200 e, although only one LED chip 200 e is exemplifiedherein. However, with reference to FIG. 10, in another embodiment, theheat generating element can also be composed of a plurality of LED chips200 f. This still belongs to a technical means adoptable in theinvention and falls within the protection scope of the invention.Furthermore, the heat dissipation plate 100 b, 100 c, and 100 d asmentioned above are applicable in other embodiments not shown herein.According to the above descriptions in the previous embodiments, peoplehaving the ordinary skill in the art can use the aforementionedcomponents to achieve the desired technical effects based on the actualrequirements.

In summary, the material of the heat-conductive material layer of theheat dissipation plate described in the invention is ceramic or silicongermanium having high thermal conductivity. The first rough surfacestructure of the first metal layer, the metal ring frame, and the secondrough surface structure of the metal substrate define a low-vacuum-levelfluid chamber. Therefore, the heat dissipation plate described in theinvention can be considered as a vapor chamber, and when the heatgenerating element (e.g., a LED chip) is disposed on the heatdissipation plate, the heat generated by the heat generating element canbe dissipated due to the two-phase flow characteristics of the vaporchamber. Thereby, the heat generated by the heat generating element canbe removed efficiently, and the efficiency and the lifetime of the heatgenerating element can be increased.

Although the invention has been described with reference to the aboveembodiments, it will be apparent to one of the ordinary skill in the artthat modifications to the described embodiments may be made withoutdeparting from the spirit of the invention. Accordingly, the scope ofthe invention is defined by the attached claims not by the abovedetailed descriptions.

What is claimed is:
 1. A heat dissipation plate comprising: aheat-conductive material layer having an upper surface and a lowersurface opposite to each other, wherein a material of theheat-conductive material layer comprises ceramic or silicon germanium; afirst metal layer disposed on the lower surface of the heat-conductivematerial layer and having a first rough surface structure; a metalsubstrate disposed below the first metal layer and having a second roughsurface structure; and a metal ring frame disposed between the firstmetal layer and the metal substrate, wherein the first rough surfacestructure, the metal ring frame, and the second rough surface structuredefine a fluid chamber, and a working fluid flows in the fluid chamber.2. The heat dissipation plate as claimed in claim 1, wherein theheat-conductive material layer further comprises at least one conductivethrough hole structure, and the at least one conductive through holestructure exposes a portion of the first metal layer and is electricallyconnected to the first metal layer.
 3. The heat dissipation plate asclaimed in claim 2, further comprising: a second metal layer disposed onthe upper surface of the heat-conductive material layer, wherein thesecond metal layer entirely covers or exposes a portion of theheat-conductive material layer.
 4. The heat dissipation plate as claimedin claim 1, further comprising: a second metal layer disposed on theupper surface of the heat-conductive material layer, wherein the secondmetal layer entirely covers or exposes a portion of the heat-conductivematerial layer.
 5. The heat dissipation plate as claimed in claim 1,further comprising: at least one opening penetrating through theheat-conductive material layer and the first metal layer andcommunicating with the fluid chamber.
 6. The heat dissipation plate asclaimed in claim 1, further comprising: at least one opening penetratingthrough the metal ring frame and communicating with the fluid chamber.7. The heat dissipation plate as claimed in claim 1, further comprising:at least one opening penetrating through the metal substrate andcommunicating with the fluid chamber.
 8. The heat dissipation plate asclaimed in claim 1, wherein a material of the first metal layer, amaterial of the metal substrate, and a material of the metal ring framecomprise copper, aluminum, or an alloy thereof.
 9. The heat dissipationplate as claimed in claim 1, wherein the first rough surface structureis a concave-convex surface structure, and a Rymax of the first roughsurface structure ranges from several micrometers to severalcentimeters.
 10. The heat dissipation plate as claimed in claim 1,wherein the second rough surface structure is a concave-convex surfacestructure, and a Rymax of the second rough surface structure ranges fromseveral micrometers to several centimeters.
 11. The heat dissipationplate as claimed in claim 1, wherein the working fluid comprises air orliquid.